The Effects of Anthropic Structures on Coastline Morphology: A Case Study from the Málaga Coast (Spain)

The Málaga coast, in the south of Spain, is a densely populated tourist destination where ports, marinas and coastal protection structures of various typologies (e.g., groins, breakwaters, revetments) and shapes (e.g., “Y”, “L”, etc., shaped groins) have been emplaced. Such structures have modified the long- and cross-shore sediment transport and produced changes in beach morphology and the evolution of nearby areas. To characterize the changes related to shore-normal structures, beach erosion/accretion areas close to coastal anthropic structures were measured using a sequence of aerial orthophotos between 1956 and 2019, and the potential littoral sediment transport for the two main littoral transport directions was determined by means of the CMS (Coastal Modeling System). Available data on wave propagation and coastal sediment transport reflect the complex dynamics of the study area, often characterized by the coexistence of opposing longshore transport directions. Accretion was observed on both sides of ports in all studied periods and groins and groups of groins presented mixed results that reflect the heterogeneity of the study area; in certain sectors where the wave regime is bidirectional, changes in the shoreline trend were observed during the study period. The study cases described in this paper emphasize the difficulties in finding clear spatial and temporal trends in the artificially induced erosion/accretion patterns recorded along a heavily modified shoreline.